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N:/MAA/Turbines:/ MAAlvin 2012 UTSR Turbine Thermal Management 100212.pptx
Turbine Thermal Management – Materials and Aerothermal Accomplishments –
M.A.Alvin
National Energy Technology Laboratory
2012 University Turbine Systems Research (UTSR) Irvine, CA
October 2-4, 2012
2
Advanced Turbines − DOE NETL Fossil Energy (FE) Goals
Advanced Technologies
Efficiency Increase, % points
Total Plant Cost,
Reduction, 2007$/kW
Cost of Electricity
Reduction, 2007¢/kWh
All Technologies Coal feed pump, gasifier materials and instrumentation, warm gas cleanup and hydrogen membrane separation,
advanced hydrogen turbines, ion transport membranes, next generation advanced hydrogen turbines, advanced sensors
and control
+8
-$800
-3.3
Advanced Hydrogen Turbine (AHT-1) Higher pressure ratio, firing temperature and design for H2-rich fuels to improve turbine performance; Increase in
power rating for economy of scale benefit
+1.8
-$190
-0.7
Advanced Hydrogen Turbine (AHT-2) Further turbine advancements increase pressure ratio, firing temperature, stage efficiencies and power rating
+1.5
-$20
-0.1
K.Gerdes, “The Potential of Advanced Technologies to Reduce IGCC Carbon Capture Costs,” GTC Conference, Colorado Springs, CO, October 7, 2009
The NETL-RUA FWP 2012.03.02 – Turbine Thermal Management project supports the DOE FE Hydrogen Turbine Technology program through component-scale testing, demonstrating technology advancements to meet the DOE advanced turbine development goals. These goals include technology development that supports 3-5 percentage point efficiency increase, and a 30 percent power increase above hydrogen-fueled combined cycle baseline machines.
3
Advanced Turbines − DOE NETL Fossil Energy (FE) Goals
R.A.Dennis, “FE Research Direction – Thermal Barrier Coatings and Health Monitoring Techniques,” Workshop on Advanced Coating Materials and Technology for Extreme Environments, Pennsylvania State University, State College, PA, September 12 - 13, 2006
Syngas Turbine
2010
Hydrogen-Fired
Turbine 2015
Oxy-Fuel Turbine
2010
Oxy-Fuel Turbine
2015
Combustor Exhaust Temp,
°C (°F )
∼1480+ (∼2700+)
∼1480+ (∼2700+)
Turbine Inlet Temp, °C (°F )
∼1370 (∼2500)
∼1425 (∼2600)
∼620 (∼1150)
∼760 (∼1400) (HP) ∼1760 (∼3200) (IP)
Turbine Exhaust Temp, °C (°F )
∼595 (∼1100) ∼595 (∼1100)
Turbine Inlet Pressure,
psig
∼265 ∼300 ∼450 ∼1500 (HP) ∼625 (IP)
Combustor Exhaust
Composition, %
CO2 (9.27) H2O (8.5) N2 (72.8) Ar (0.8) O2 (8.6)
CO2 (1.4) H2O (17.3) N2 (72.2) Ar (0.9) O2 (8.2 )
H2O (82) CO2 (17) O2 (0.1) N2 (1.1) Ar (1)
H2O (75-90) CO2 (25-10)
O2, N2, Ar (1.7)
4
Turbine Thermal Management – Programmatic Goals –
Overall Project Objectives Turbine Thermal Management consists of four technical subtasks that focus on a critical technology development in the areas of heat transfer, materials development, and secondary flow control. Collectively these projects contribute to achieving increased percentage point plant
efficiency gain by permitting a higher turbine firing temperature as a result of Realizing more effective airfoil cooling Development and utilization of extreme temperature thermal barrier coating
protection systems System leakage flow reduction
5
Turbine Thermal Management
Strategic Center for Coal
Richard Dennis, Technology Manager Patcharin Burke, Technology Monitor
Heather Quedenfeld, Division Director PSD
Office of Research & Development
Cindy Powell, Director Geo Richards, Focus Area Lead
Randall Gemmen, Federal Project Monitor Mary Anne Alvin,Technical Coordinator
Task 1 −Project
Management
Task 2 − Aerothermal
& Heat Transfer
Task 3 − Coatings &
Materials Development
Task 4 − Design
Integration & Testing
Task 5 − Secondary Flow Rotating Rig
2.1 Internal &
Transpiration Cooling 2.2 Trailing Cooling 2.3 Film Cooling
3.1 Bond Coat & Extreme
Temperature Coatings 3.2 Diffusion Barrier
Coatings 3.3 Advanced Material
Systems
4.1 Concept
Manufacturing 4.2 NETL Rig Testing
5.1 Facility Development 5.2 Test Campaigns
1.1 Project Management
Plan 1.2 Meetings 1,3 Reports
URS Regional University Alliance
(RUA) UPitt, VT, PSU
6
NETL-RUA Turbine Thermal Management Project
Task Goals/Objectives:
Perform a collaborative materials and component development effort that integrates thermal protection systems − thermal barrier coatings, bond coats and diffusion protection layers − utilizing advanced but conventional substrate alloys, with advanced internal heat transfer surfaces and novel film cooling architectures Develop advanced , commercially manufacturable material systems: Stable in high
temperature (>1400ºC), high steam-content combustion gas environments. Develop manufacturable cooling technologies: Increase heat transfer enhancement factor
nearly 5 times the smooth channel baseline Develop core competency: Design and proof-of-concept testing of the NETL-RUA Near Surface
Embedded Micro-Channel (NSEMC) Concept1 Develop manufacturable tripod hole designs: 50% reduction in film cooling flow usage Utilize state-of-the-art manufacturing technologies: Design and fabrication of coupons and
airfoils for proof-of-concept testing Address alternate advanced material systems: ODS & CMC
Design/construct/operate an NETL-RUA world-class rotating rig for studying leakages, secondary flows and internal heat transfer in high speed rotating airfoils Demonstrate reduction of secondary flow leakages to reduce fuel burn (i.e., 3.34% leakage
reduction = 1.95% fuel burn reduction)
1 Patent Application submitted, December 27, 2011
7
NETL-RUA Turbine Thermal Management Project − Overall Approach −
Pratt & Whitney
PSU Secondary
Flow Rotating Rig
VT Film Cooling
Siemens Ames
UPitt Internal
&Transpiration Cooling
Trailing Edge
NASA Testing & Materials
Howmet/ PCC
WPC Testing
Mikro Systems
CFI
CMCs & ODS
Ames
Caterpiller Pratt &
Whitney
Pitt Diffusion
Barrier Coating
Development
NETL Bond Coat &
Temp Overlayer
Development NETL Aerothermal & Material
Integration Manufacturing
Rig Testing
Materials Development
Aerothermal & Thermal
Management
Rotating Rig
The Turbine Thermal Management project leverages government, academic, and
industrial collaborations working synergistically in different aspects of
aerothermal and materials issues to achieve the set overall goal through state-of-the-art
analysis, modeling and testing. The program is uniquely structured to address:
(1) Development and Design of Aerothermal and Materials Concepts in FY12
(2) Design and Manufacturing of these advanced concepts in FY13
(3) Bench-Scale/Proof-of-Concept Testing of these concepts in FY13-FY14 and beyond
8
Turbine Thermal Management
Coatings and Materials Development
M.A.Alvin, NETL
K.Klotz and B.McMordie, Coatings for Industry B.Gleeson and X.Wu, University of Pittsburgh B.Warnes, Corrosion Control Consultants, Inc.
Stakeholders
Dr. Carlos Levi, UCSB Dr. Yongho Sohn, UCF
Dr. Anand Kulkarni, Siemens Energy Dr. Surinder Pabla, GE
Aerothermal Heat Transfer & Secondary Flow Rotating
Rig
M.Chyu, S.Siw and N.Miller, University of Pittsburgh S.Ekkad, C.LeBlanc and S.Ramesh, Virginia Tech
K.Thole and M.Barringer, J.Schmitz, A.Glahn, D.Cloud, K.Clark, Penn State University/Pratt & Whitney
M.A.Alvin, D.Straub, S.Lawson, K.Caselton and T.Sidwell, NETL
Stakeholders Dr. Ron Bunker, GE; Dr. John Marra, Siemens Energy Dr. Klaus Braun, SwRI; Dr. Jim Heidmann, NASA GRC
Dr. Atul Kohli, PW; Dr. Dick River, WPAFB Dr. Jim Downs, FTT; E.Razinsky, Solar Turbines
T.Shih, Purdue University
9
Turbine Thermal Management
Coatings and Materials Development
NETL Coating System Composite Architecture NETL-CFI Diffusion Bond Coat Development Diffusion Barrier Coatings High Temperature Thermal Flux Testing of Advanced
Composite Architectures
Aerothermal & Heat Transfer
Internal Airfoil Cooling Trailing Edge Cooling Tripod Hole Film Cooling NETL High Temperature, Pressurized Rig Secondary Flow Rotating Rig
10
NETL Coating System Composite Architecture − Extreme Temperatures/Steam-Containing Environments −
Extreme Temperature Overlay - Plasma sprayed: ZrO312: ZrO2-2.8wt%Y2O3-3.3wt%Gd2O3-3.6wt%Yb2O3 or HfO2-14mol%Y2O3-3mol%Gd2O3-3mol%Yb2O3
11
Bond coat development criteria Reduced bond coat cost in comparison to current SOTA bond coat systems Enhanced long-term high temperature oxidation resistance (1100ºC)
Modification of CFI’s Alseal wet sprayed commercial product
Bond coat development at NETL and CFI addressed diffusion bond coat
systems fabrication Low & high firing temperatures (high & low activity) Without/with the addition of Hf Various concentrations of Hf Variations on the number of coating passes
NETL-CFI Diffusion Bond Coat Development
Background – A1D Bond Coating
12
NETL-CFI Diffusion Bond Coat Development
Background – A1D Bond Coating
Alseal A1D consists of aluminum,
silicon and hafnium powder in an inorganic phosphate binder
When heated to 885°C or more, the metal melts and reacts with the substrate to form a densified NiAl
Undiffused reactants form a loose crust (bisque)
Aluminizing with Alseal A1D
13
NETL-CFI Diffusion Bond Coat Development
As-Manufactured A1D
Uniformity of bond coat/interdiffusion thickness for
all manufactured A1D series coupons: ~70-75 µm/ ~20-25 µm (interdiffusion zone)
Bond coat: Ni-rich β-NiAl matrix with additional elements in solid solution (Cr, Co and small amounts of refractory metals)
Finely dispersed refractory-metal rich precipitates (Ta, W, Mo, Re) throughout the coating indicating that the bond coat is inwardly grown
74 μm
21μm
As-Manufactured
Ni-40Al-3.5Cr-5Co-3Si (at%)
Ni-33Al-9.5Cr-7Co-1Mo (at%)
René N5
14
Comparison of Diffusion Bond Coat Performance − Cyclic Oxidation Testing at 1100°C in Static Air −
The oxidation wt% change data was compared with SOTA β(Ni,Pt)Al, and Pt+Hf-Mod γ-γ’ diffusion bond coatings
A1D exceeded A1’s cycle time-to-failure, Pt+Hf-Mod γ-γ’ s cycle time-to-failure,
and at test termination, exceeded SOTA β(Ni,Pt)Al’s cycle time-to-failure
15
Comparison of A1D and Current SOTA Diffusion and Overlay Bond Coat Systems
Bond Coat System
A1D
β-(Ni,Pt)Al
(SOTA)
MCrAlY (SOTA)
Slow Growing & Adherent TGO
0
√√
0
Maintain Planar Nature • Absence of Rumpling
(Ratcheting) • Retention/Adherence of
Applied YSZ, Extending Service Operating Life
√√
X
√
Compatibility with Substrate
• No Detrimental Secondary Reaction Zone
• Retention of Mechanical Properties
√
X
X
Cost Effective √√√ √ √√
Forward Direction Co-doping to enhance extended oxidation resistance performance
Integration with diffusion barrier coatings Application to alternate substrate nickel-based superalloys & single crystals
16
Diffusion Barrier Coatings DBC Criteria
Extended high temperature oxidation resistance (8,000-30,000 hours) Minimal interdiffusion between substrate and surface modified region
Diffusion barrier (i.e., Re-Cr-Ni compositions) to preclude aluminum-based coating and
heat resistant superalloy or single crystal substrate interdiffusion and sustain protective coating properties
alloy
diffusion barrier (σ-based)
Al reservoir (A1D β-NiAl)
alloy
diffusion barrier (σ-based)
Al-rich A1D source Ni-rich overlayer heat treat
Preparation of A1D / DBC System
17
Diffusion Barrier Coatings with A1D − NETL-CFI-UPitt-Ames −
− A1D Specifications for DBC Integration −
Test Campaign No.1 PWA 1484/Gen-1 DBC/A1D
Received PWA 1484 with Ni-electroplated layer over Gen-1 DBC
(T.Nariata courtesy B.Gleeson) 20 cycles of 1100ºC thermal cycling led to significant degradation of
the coated surfaces
As-Manufactured
Coupons and micrograph courtesy of Brian Gleeson
18
Diffusion Barrier Coatings with A1D − NETL-CFI-UPitt-Ames −
− A1D Specifications for DBC Integration −
Test Campaign No.2 René N5/Gen-1 DBC
Received René N5/T.Narita’s Gen1-
DBC/~5µm electroplated-Ni layer
CFI used standard grit blast on electroplated-Ni layer for surface preparation prior to A1D application
Characterization intended to address: Thickness of the remaining electroplated-
Ni layer that was deposited on the DBC layer
Interaction of the A1D with the electroplated-Ni Composition, microstructure, diffusion
bond coat thickness
Plated Ni for protection
N5 (small sized sample)
γ’
γ + γ’ (precipitated from g-phase during cooling)
γ’ dark phase
γ bright phase
Coupons, micrograph, and EDAX profile courtesy of Brian Gleeson
As-Manufactured DBC
19
Diffusion Barrier Coatings with A1D − NETL-CFI-UPitt-Ames −
− A1D Specifications for DBC Integration −
Test Campaign No.2 As-Manufactured René N5/ Gen-1 DBC/A1D
Surface preparation Minimal fracture of DBC surface with 40 psi, 100
grit alumina
Diffusion of A1D into & through the DBC into the René N5 substrate resulted
Re-rich precipitates were visible on the top of the coating, but no continuous DBC layer formed
39Re-30Cr-16Al-14Ni
Ni-50Al
Ni-45Al A1D
20
Diffusion Barrier Coatings
Test Campaign No.3 As-Manufactured Haynes 214/Gen-2 DBC
DBC powder development at Ames Lab via
high energy mechanical milling (Zoz mill)
σ-DBCs were deposited by Caterpillar Inc’s Technical Center via HVOF Thick coating: 50Re-24Cr-26Ni (at%) Thin coating: 72Re-14Cr-11Ni (at%)
Al reservoir was a Praxair Ni-343 overlay
(67Ni-22Cr-10Al-1Y (wt%)) deposited by HVOF
Representative cross-sectional
micrographs of the as-manufactured (a) thin and (b) thick DBC systems
40Re-40Cr-20Ni (at.%) mixture mechanically milled at the Ames Laboratory using a Zoz Mill
21
Diffusion Barrier Coatings
Test Campaign No.3 As-Manufactured Haynes 214/Gen-2 DBC
Bench-scale furnace testing at 1100°C
Thick Coating: Little change in Re content after 100 hrs Small amount of Cr-enrichment at
NiCrAlY/DBC interface
Bench-scale furnace testing at 1200°C Thick Coating: Re diffused from the DBC to the NiCrAlY
coating, and Al from the coating to the DBC Measurable change in the DBC
composition with increasing exposure time, as well as temperature
Accelerated testing at higher temperatures cautioned
Cross-sectional micrographs of the (a) thin and (b) thick DBC systems after
100 hrs exposure at 1100°C (∼2010°F)
22
Diffusion Barrier Coatings
Test Campaign No.3 As-Manufactured Haynes 214/Gen-2 DBC/A1D
Application of A1D onto thick DBC A1D diffusion bond coat was seen to be retained
along the exterior surface of the DBC-coated Haynes 214 coupon
Formation of a 50 µm external Ni3Al layer Outward diffusion of DBC Inward diffusion of DBC Interface processing needs to be addressed
Materials were not available for thermal cyclic testing
As-Manufactured with A1D
23
A1D retained along external DBC surface Slurry formed Ni3Al (22.6 at% Al) rather
than NiAl as it diffused on Ni5Al
Interconnected porosity remaining in the Ni5Al layer after diffusion (between arrows on lower left) micrograph, allowed severe internal oxidation at 1100°C Interface processing issues to be
resolved
Coating partially detached from substrate after 129 cycles at 1100ºC in static air
Grain boundary oxidation of Haynes 230 (DBC interface) at 1100ºC Selection of substrate materials &
Accelerated testing at higher temperatures cautioned
As-Manufactured 1100oC 100 hr
Diffusion Barrier Coatings
Test Campaign No.4
Haynes 230/Thermal spray ReNiCr (DBC)/Thermal spray Sulzer Metco 450 Ni5Al / A1D
24
High Temperature Thermal Flux Testing − Westinghouse Plasma Corporation & NASA GRC −
René N5/MCrAlY/EBPVD 022508 177 hrs 23 min
WPC High Temperature Thermal Flux Testing
NASA GRC High Temperature Thermal Flux Testing
25
Composite Coating Architecture (APS) − Thermal Cycling/Thermal Gradient −
Temperature, °C
Test No.
Substrate & Coating Composition
Steam
Back
Coupon Surface
Bond Coat Surface or Interface
YSZ Surface
Overlayer Surface
Visual Inspection
1-4
René N5/LPPS MCrAlY/ Howmet APS YSZ/
APS ZrO2-2.8wt%Y2O3-3.3wt%Gd2O3-3.6wt%Yb2O3
1000
1115
1482
Intact after 50
Cycles(a)
1-3
René N5/A1D/ Howmet APS YSZ/
APS ZrO2-2.8wt%Y2O3- 3.3wt%Gd2O3-3.6wt%Yb2O3
1018
1120
1482
Intact after 50
Cycles(b)
1-5
René N5/A1D/ Howmet APS YSZ/
APS ZrO2-2.8wt%Y2O3-3.3wt%Gd2O3-3.6wt%Yb2O3
√ 1050 1135 1482 Failed after 49 Cycles(c)
(a) The estimated initial coating thermal conductivity was ~ 0.94 W/m-K; Thermal conductivity increased to ~1.14 W/m-K after the 10 cycle test; Thermal conductivity reduction in the further cycles test (reduced to ~1.10 W/m-K at ~28-29 cycles)
(b) The estimated initial thermal conductivity of the coating was ~ 0.97 W/m-K; Thermal conductivity increased to ~1.13 W/m-K after the first cycle, reaching a maximum ~1.15 W/m-K in the first 5 thermal cycles ; Increase possibly due to sintering and /or porosity reduction within the top coat layers; Very slight conductivity reduction resulted during further thermal cyclic testing (1.12 W/m-K after 50 hrs of testing); Reduction possibly due to defect formation (i.e., gaps; microcracks) within the topcoat or along TGO interface
(c) The estimated initial coating thermal conductivity was ~ 0.99 W/m-K; Thermal conductivity increased to ~1.21 W/m-K after the first cycle test ; Thermal conductivity reduction occurred during continued cyclic testing (reduced to ~0.7 W/m-K at ~38-39 cycles) due to partial coating delamination (average measured Tsurface 1520-1550°C, Tinterface up to ~975°C and Tmetal back ~871°C); The coating had half spallation at 49th cycle; Remaining coating visually appeared to be intact
26
Test No. 1-4: René N5/LPPS NiCoCrAlY/APS
YSZ/ZrO312, Air, 50 hrs Thermal Cycling The coating visually appeared to be intact after testing Very minor edge buckling/spalling occurred Microstructural Characterization Little evidence of TBC coating failure
Although features of aluminum depletion in the bond coat
were evident, a continuous alumina surface scale is maintained (∼5-10 µm)
Degradation within the NiCoCrAlY coating Numerous large internal oxide formations
No indication of cracking or delamination of the porous
bilayer ceramic coating Some flaking of the porous plasma sprayed ceramic surface
T1-4: Coupon tested in air at ~1482ºC (2700ºF), 50, 1 hr
cycles
ZrO312
YSZ
NiCoCrAlY
René N5
Composite Coating Architecture (APS)
27
Test No. 1-3: René N5/A1D/APS YSZ/ZrO312, Air, 50 hrs
Thermal Cycling The coating visually appeared to be intact at test termination
Microstructural Characterization Little evidence of TBC coating failure
Although features of aluminum depletion in the bond coat were
evident, a continuous alumina surface (∼<5 µm) scale is maintained
Absence of internal oxidation within the A1D diffusion bond coat A1D surface planarity retained No SRZ formation
No indication of cracking or delamination of the porous bilayer
ceramic coating Some flaking of the external ceramic surface
T1-3: Coupon tested in air at ~1482ºC (2700ºF), 50, 1 hr
cycles
ZrO312
YSZ
A1D
René N5
Composite Coating Architecture (APS)
Comparison of A1D & NiCoCrAlY 1100°C Laser Flux Tests: NiCoCrAlY has more extensive internal oxidation than A1D A1D is likely to endure more thermal cycling prior to failure than
NiCoCrAlY
28
Test No. 1-5: René N5/A1D/APS YSZ/ZrO312/Steam, 50 hrs Thermal Cycling
The coating had half spallation at 49th cycle; Remaining coating visually appeared to be intact
Tsurface 1520-1550°C Microstructural Characterization Delamination occurred in the TBC layer adjacent to the YSZ-
bond coat interface YSZ remained attached to the bond coat surface Crack formations were evident in the ZrO312 layer
Absence of crack formations within the A1D bond coat ∼3-7 µm alumina formation on A1D Planarity of A1D surface retained No SRZ formation
T1-5: Coupon tested in water vapor at ~1482ºC (2700ºF), 49, 1 hr cycles
Composite Coating Architecture (APS)
Prior art suggests ceramic coating delamination is the result of thermal mismatch between the bond coat and TBC layer If this were the sole source for failure, failure should
have occurred in Test 1-3 and Test 1-4 (air) Prior art also suggests that water vapor increases the
rate of alumina growth at HT As internal stress in TBC increases as alumina
growth increases, failure is likely Note: No apparent significant increase in measured
alumina thickness (∼<5 μm to ~5 μm ) Issues raised: Coating application – A1D/YSZ interface
surface roughness; Surface over-temperature exposure; Fixturing (clamping) of coated coupon in steam rig; Uniformity of laser intensity; Steam port injection location relative to delamination; Edge effect failure
29
Composite Coating Architecture (EBPVD) − Thermal Cycling/Thermal Gradient −
Temperature, °C
Test No.
Substrate & Coating Composition
Steam
Back
Coupon Surface
Bond Coat Surface or Interface
YSZ Surface
Overlayer Surface
Visual Inspection
2-4
René N5/A1D/
P&W EB-PVD YSZ
√
975-1000
1100-1140
1300
−
Spalled after 20 Cycles(a)
2-5
René N5/A1D/ P&W EB-PVD YSZ/
EB-PVD ZrO2-2.8wt%Y2O3-3.3wt%Gd2O3-3.6wt%Yb2O3
√
900
1120
−
1450-1460
Intact after 50 Cycles(b)
2-3
René N5/A1D/ P&W EB-PVD YSZ/
EB-PVD HfO2-14mol%Y2O3-3mol% Gd2O3-3mol%Yb2O3
√
990
1120
−
1500-1520
Spalled after 50 Cycles(c)
(a) Surface temperature increased (maximum surface temperature ~1400°C) at the 20th cycle due to a reduced steam flow; Interface maximum temperature ~1180°C for two cycles, and coating had local spallation, then quickly resulting in larger area buckling; The test terminated with the spalled thermal barrier coating.
(b) Thermal conductivity initially increased due to sintering and later decreased due to possible minor coating delamination; Further cycling showed relatively stable or very minor reductions in thermal conductivity values.
(c) Surface temperature increased (surface temperature over 1575°C) at the 6th - 13th cycle due to a sudden reduced steam flow; Interface maximum temperature around 1150°C for eight cycles, no visual coating damage with the over temperature cycles; Further cycling showing slightly conductivity reduction indicating some interface damage
30
Test No. 2-4: René N5/A1D/P&W EB-PVD YSZ Spalled Area Evidence of extensive cracking in the YSZ Exposed surface contains alumina, nickel,
chromium, as well as adherent remnants of YSZ
Tinterface ∼1180ºC (2 cycles)
Non-Spalled Area Segmented structure of EB-PVD TBC Areas with partial detachment of the TBC from
the bond coat; Areas where TBC remains attached
Failure of the TBC involved fracture of the TGO and subsequent detachment of the TBC
Loss of aluminum from the A1D bond coat caused the formation of γ’ along the metal-oxide interface, along the grain boundaries, and within the coating grains
Composite Coating Architecture (EBPVD)
T2-4 Coupon tested in water vapor at ~1300ºC, 20, 1 hr cycles
31
31
Test No. 2-5: René N5/A1D/P&W EB-PVD 7YSZ/EB-PVD ZrO2-2mol% Y2O3-1mol%Gd2O3-1mol%Yb2O3
Surface Irregular surface with extensive cracking Surface roughness may be related to columnar EBPVD
structure
Cross-Sectional Analysis Bond coat is silicon modified aluminide ∼23 µm alumina TGO formation If >10 µm, then TGO is prone to cracking
Zirconia appears to be dense adjacent to the TGO, while the remainder to the EBPVD is columnar
Large cracks between the bond coat and TGO layer ∼10 cycles, thermal conductivity decreased due to
minor cracking/coating delamination Aluminum depletion in the bond coat led to Ni3Al (γ’) at
coating surface Coating degradation related to growth stress and
thermal stress in the TGO layer vs degradation of the bond coat
T2-5 Coupon tested in water vapor at ~1450ºC, 50, 1 hr cycles
Composite Coating Architecture (EBPVD)
32
Test No. 2-3: René N5/A1D/P&W EB-PVD YSZ/HfO2-14mol%Y2O3-3mol%Gd2O3-3mol%Yb2O3
Spalled Area Extensive cracking of the ceramic layer Spallation at the center of the heated area Residual ceramic is adherent to the TGO which
contains both alumina and zirconia, or solely alumina
Testing interval when Tsurface >1575°C with Tinterface ~1150°C
Non-Spalled Area Segmented structure of the EBPVD TBC Large crack formations with removal of the TBC Bi-layer TBC architecture Complex ceramic on top surface of YSZ
Little evidence of a continuous alumina layer on the A1D bond coat Oxide between the stabilized zirconia and the
diffusion aluminide appears to be a mixture of alumina and stabilized zirconia grains
TGO appears to be extensively fractured TBC failure may have been caused by growth
and coalescence of the TGO crack formations
Composite Coating Architecture (EBPVD)
T2-3 Coupon tested in water vapor at ~1500-1520ºC, 50, 1 hr cycles
33
Leakage Combusted Gas Path
Internal Secondary Air Supply
Secondary Flow Leakages
Zero Leakage Secondary Air System at PSU NETL’s High Temperature,
Pressurized Aerothermal Test Facility
Heat Transfer Test Facility at Pitt
VT’s Cascade, Low Speed Wind Tunnel, and Tripod Hole Configurations
NASA GRC High Temperature Thermal Flux Testing
NETL-RUA Turbine Thermal Management Project
Westinghouse Plasma Corp High Temperature Thermal Flux Testing
34
NETL-RUA Turbine Thermal Management Project – Airfoil Internal Cooling –
Heat Transfer Test Facility at Pitt
Develop cooling technologies that are capable of yielding a heat transfer enhancement factor nearly 5 times the smooth channel baseline and which are reasonably manufacturable
Develop core competency, design and proof-of-concept testing of the NETL-RUA Near Surface Embedded Micro-Channel (NSEMC) Concept (Patent Application submitted, December, 2011)
Triangular, semi-circular, and circular pin-fin arrays assessed as internal turbulators for enhanced internal turbine airfoil heat transfer enhancement Triangular pin-fin array has higher heat transfer Presence of sharp edges that generate additional
wake, resulting in better flow mixing
NSEMC models have been designed and constructed Addressing hole diameter, location, surface turbulators Initial design assessed in terms of manufacturability
h (W/m2-K)
35
a) Zig-Zag Channel with 70o Turns b) Zig-Zag Channel with 90o Turns
c) Zig-Zag Channel with 110o Turns
NETL-RUA Turbine Thermal Management Project – Airfoil Trailing Edge Cooling –
ANSYS CFD modeling and experimental testing
Designs consisting of 110° turning angle zig-zag passages numerically exhibited the highest heat transfer, h, in comparison to 70° and 90° turning angle zig-zag passages.
The heat transfer performance in the zig-zag channel is enhanced after every turn within the flow domain due to turbulence and mixing
Overall heat transfer enhancement in the zig-zag channel is enhanced by ∼1.7 times in comparison to the fully developed smooth channel
The pressure loss of the zig-zag channel seems to be insensitive to the Re = 15,000-30,000
Rib-turbulators throughout the entire zig-zag channel, increase heat transfer enhancement by ~two-fold in comparison to the smooth zig-zag channel
Where all passages contain rib-turbulators, pressure loss is ∼30-90% higher than that of the zig-zag smooth counterpart
36
Parameters explored included the spacing between hole groups and the divergence angle of the outside legs of the tripod design
NETL-RUA Turbine Thermal Management Project – Airfoil Film Cooling –
VT’s Cascade, Low Speed Wind Tunnel, and Tripod Hole Configurations
Utilize the tripod hole design to demonstrate a 50% reduction in film cooling flow usage
Aerodynamic benefits: The tripod holes showed minimal disruption to the downstream flow
pattern at all blowing ratios, while the cylindrical and shaped holes disrupted the flow pattern, especially at high blowing ratios
With almost half the coolant mass flow, the tripod holes proved to have better cooling effectiveness as a result of better lateral diffusion in the near hole region
Tripod hole manufacturability was assessed. No issues with construction identified.
A thermo-mechanical stress analysis was conducted for the cylindrical and tripod hole designs. The magnitude of the stress was similar for both cases, indicating that thermal stresses will not be the limiting factor of the tripod design.
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NETL-RUA Turbine Thermal Management Project – High Temperature, Pressurized Testing –
NETL’s High Temperature, Pressurized Aerothermal Test Facility
FY12 – Validated surface temperature measurements with optical pyrometer and thermcouples
Utilize state-of-the-art manufacturing technologies, construct “coupon-scale” integrated material/component systems, and demonstrate performance in NETL’s aerothermal test facility
Initiate advanced material system (CMC & ODS) development/OEM interactions/testing. Support NETL-RUA patent application NSEMC
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NETL-RUA Turbine Thermal Management Project – Secondary Flow Rotating Rig –
Design/construct/operate an NETL-RUA world-class rotating rig for studying leakages, secondary flows and internal heat transfer in high speed rotating airfoils
Demonstrate capabilities for reduction of secondary flow leakages in power generation turbines to reduce fuel burn (i.e., 3.34% leakage reduction = 1.95% fuel burn reduction)
1.5 stage high pressure rotating turbine (vane/blade/vane) to study The influence of leakage flows from the internal air system on
turbine stage aerodynamics and heat transfer The cooling flow performance within airfoils under rotation and
with internal air system leakage The impact of separately optimized designs (aero, rim cavity,
durability) versus combined system optimized designs
Leakage
Combusted Gas Path
Internal Secondary Air Supply
Secondary Flow Leakages
Zero Leakage Secondary Air System at PSU
F.S.Elliott P700 1,500 Horsepower Centrifugal Compressor System
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Acknowledgments
We acknowledge Mr. Richard Dennis and Ms. Rin Burke at DOE NETL for their support
Collaborative efforts are being performed under the NETL-Regional University Alliance (RUA) Contract DE-FE-0004000
Turbine Thermal Management Field Work Proposal Number 2012.03.02
This presentation was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial
product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States
Government or any agency thereof.